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CAMBRIDGE INTERNATIONAL EXAMINATIONS
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GCE Ordinary Level
MARK SCHEME for the October/November 2013 series
5070 CHEMISTRY
5070/42
Paper 4 (Alternative to Practical), maximum raw mark 60
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of
the examination. It shows the basis on which Examiners were instructed to award marks. It does not
indicate the details of the discussions that took place at an Examiners’ meeting before marking began,
which would have considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner
Report for Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2013 series for most IGCSE,
GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level
components.
Page 2
1
Mark Scheme
GCE O LEVEL – October/November 2013
Syllabus
5070
Paper
42
(a) 28, 23 (1) 5 (1)
[2]
(b) (i) exothermic (1)
[1]
(ii) vertical line labelled ∆H must go to same level as products (1)
horizontal line below reactant line, ignore any labelling (1)
(horizontal line above reactant line i.e. endothermic, 1st mark only can score.)
[2]
(c) (i) blue (ignore any initial colour) (1)
[1]
(ii) pH meter/pH or universal indicator/pH paper (1)
[1]
(iii) 10–14 (1)
[1]
[Total: 8]
2
(a) nitric (acid), HNO3 (1) (both)
[1]
(b) heat/warm/evaporate/boil/leave in sun (1)
to crystallisation point/saturation point/evaporate some (but not all) of the water/
leave solution to cool/leave to crystallise (1)
wash and dry crystals (1)
[3]
(c) (i) molar mass of NH4NO3 = 80 (1)
28/80 × 1000 = 350 (g) (1)
[2]
(ii) (350/28) × 24 = 300 (dm3) (1)
[1]
(d) ammonium sulfate, (NH4)2SO4 (1)(both)
[1]
(e) NH4+ (1)
warm with (aq) NaOH (1)
NH3 turns litmus blue OR gas turns litmus blue (1)
[3]
[Total: 11]
3
(b) (1)
[Total: 1]
4
(d) (1)
[Total: 1]
5
(a) (1)
[Total: 1]
6
(b) (1)
[Total: 1]
© Cambridge International Examinations 2013
Page 3
7
Mark Scheme
GCE O LEVEL – October/November 2013
Syllabus
5070
Paper
42
(a) 1.65 (g) (1)
[1]
(b) (i) (to prevent) oxidation of Fe2+ ions or to prevent Fe2+ being converted to Fe3+/
Fe(III) (1)
[1]
(ii) hydrogen (1)
pops in a flame/lighted splint (1)
[2]
(c) (i) green/colourless (1)
(ii) purple/pink (1)
(d) 27.8
0.0
27.8
32.1
5.7
26.4
[2]
47.3
20.7
26.6
1 mark for each correct
row or column to
benefit of candidate (3)
mean titre = 26.5 (1) cm3
[4]
(e) 0.00053 (moles) (1)
[1]
(f) 0.00265 (moles) (1)
[1]
(g) 0.0265 (moles) (1)
[1]
(h) 1.484 (g) (1)
[1]
(i) 89.7–90.(0)(%)(1)
[1]
[Total: 15]
8
(a) colourless solution (1)
(b) (i) white ppt (1) soluble in excess(1)
(c) (i) white ppt , insoluble in excess (1) (both)
(d) Ba(NO3)2 or BaCl2 (1) + HCl or HNO3 (1)
(incorrect formula negates correct name and vice versa)
white ppt (1) (dependent on use of barium salt)
conclusion Al2(SO4)3 (1)
[8]
[Total: 8]
© Cambridge International Examinations 2013
Page 4
9
Mark Scheme
GCE O LEVEL – October/November 2013
Syllabus
5070
Paper
42
(a) carbon/graphite/platinum (1)
[1]
(b) E or negative or cathode (1)
[1]
(c) a gas is evolved/oxygen gas evolved/bubbles/effervescence/fizzing (1)
[1]
(d) (i) 1.5, 2.0, 2.25, 2.25, 2.25 (1) all correct.
[1]
(ii) all points plotted correctly (1)
two intersecting straight lines (2) (1 mark for one straight line)
[3]
(iii) 32 (min) (1)
[1]
(iv) 45 (min) (1)
[1]
(e) (i) blue (1)
[1]
(ii) colourless (1)
[1]
(f) sloping line continues in a straight line upwards all the way to t = 70, labelled S(1).
[1]
(g) blue (all shades but not combinations such as greeny blue etc.)(1)
concentration of Cu/Cu(II)/Cu2+ ions remains constant
OR concentration of electrolyte remains constant
OR explanation based on copper/copper ions being removed and deposited into the
solution (1)
[2]
[Total: 14]
© Cambridge International Examinations 2013